Theft or misappropriation of personal access numbers, passwords, or personal identification numbers (PIN's) often occurs where businesses provide a user (or customer) with remote access to a service or product. In the case of financial services, the password is a PIN. For example, a bank issues a PIN and an account number for use in accessing a plurality of cash disbursement machines (e.g. Automatic Teller Machines--ATM's). Cash disbursement machines are typically linked to a central computer that performs the access authorization process.
Generally, access authorization occurs by inserting a card containing a magnetically stored account number or other user account information into the remote ATM. Once the magnetic card reader in the ATM reads and matches the stored account number with a valid account number, the ATM prompts the user to input the user's PIN. If the entered PIN and account number pair correspond to a valid PIN and account number pair previously stored in a user file, access to the account is granted. The unique PIN assigned to or chosen by the user is typically memorized by the user and is not known to any other entity other than an account access administrator that issues the PIN.
Generally, theft occurs because the PIN is a static or fixed identification key in that the user enters the same identification key (i.e., PIN) each time access is desired. An unscrupulous onlooker may see the PIN being entered (or a password as in the case of a computer terminal, mobile telephone, or equivalent access terminals) and may steal the card whereafter the thief may gain access to the system. Alternatively, as in the case of a telephone calling card, the card is not required to access the account.
One known method for protecting card users allows the user to choose a PIN without the knowledge of the account access administrator. This further reduces the number of persons that know the user's PIN. Such methods also use an encoding algorithm to encode the PIN and subsequently store the encoded version of the PIN on the card. The encoding algorithm is known only to the account access administrator and uses both static and dynamic encoding keys as variables to generate an encoded PIN. A dynamic variable changes as a function of an event or environmental situation which may include a new account balance or the date of the use of the card. Consequently the encoded PIN is more random and less predictable.
However, the user still enters the undisguised static PIN whereafter the system decodes the encoded PIN stored on the card and grants access to the system if the decoded PIN and the undisguised static PIN match. Therefore the problem of an unscrupulous onlooker gaining access to the system from seeing the PIN and stealing the card still exists.
Other access methods require additional hardware components and also include the use of time dependent variables (time of day data), as encoding keys for a predetermined algorithm. Generally in such a system, both the user and an authorization center (e.g. ATM) use a separate computer to generate a "non-predictable code" based on a predetermined ciphering algorithm. This algorithm is stored in both computers.
The PIN and account number are entered by the user into the hand held computer that stores the predetermined algorithm (the same algorithm used by the verification computer). The algorithm obtains the time dependent variable from its internal clock and generates the "non-predictable" code that is then entered into the ATM by the user. Each computer requires an internal clock to generate the dynamic time dependent variable. The user receives ultimate access when a match between the two generated codes occurs. The algorithm uses a plurality of static variables and a dynamic time dependent variable as its ciphering keys.
However, this method requires a user to obtain a separate computer to access a desired system and requires each of the separate computers to maintain timing devices for time dependent variable generation and synchronization. This becomes costly and complicated when users require inexpensive and easy access to a desired service or product.
There exists a need for a secure access method and system that substantially prevents an onlooker from determining secret access data while minimizing the hardware and access time needed by the user to receive complete access to a limited access system.